Mine prop



Oct. 12, 1954 BIGELQW I 2,691,503

MINE PROP Filed March 18. 1950 00571.9 94 Dl-FLECTOI? FLA "GE INVENTOR.flog f fliyelow.

A TT'O/QNEY Patented Oct. 12, 1954 MINE PROP Roy S. Bigelow, Chicago,Ill., assignor to Goodman Manufacturing Company, Chicago, 111., a'corporationof Illinois Application'March 18, 1950, Serial No. 150,878

1 Claim. 1

This invention relates to props and particularly to props of the typeemployed in mines to span the space between the ground and roof forholding up the roof and for holding down various kinds of equipment,for-example shaker conveyor.

This application is a continuation-in-part of applicants priorapplication, Serial No. 552,243, filed September 1, 1944, Patent No.2,630,902, .and relates to the prop disclosed but not claimed in thatprior application.

A principal object of this invention is to provide a prop which can beput up and taken down by a single man with a minimum of time and effort.

An important feature of the improved prop is that it comprises a doublyexpandable structure having manually extensible screw means for quickinitial adjustment of the prop to the height of the roof, and extensiblehydraulic means for applying a subsequent holding load between theground and roof.

Another, ancillary, object is the provision of a screw-hydraulic prop ofthe above-mentioned character which will operate without jamming orclogging by dust normally encountered in mines.

Other objects and advantages will be-apparent from the followingdescription taken in connection with the figures of the drawing inwhich:

Figure 1 is a perspective view of a prop illustrating one embodiment ofthe present invention, and

Fig. 2 is an enlarged fragmentary cross sectional view of the hydraulicportion of the prop shown in Fig. 1.

Referring now in more detail to the drawing, the embodiment illustratedcomprises a doubly expandable structure I8 having manually operablescrew means 2l carried atop hydraulic means 8|.

The screw means comprises, in this instance, a rod or ram screw 83having external threads 24 formed thereon and engaged with internalthreads 26 formed in wing nut member 86. The latter carries anupstanding tubular extension 84 and an upper roof-engaging shoe 85.Thus, it will be apparent that, by grasping one of the wing nut handles3|, and spinning the wing nut rapidly, the upper portion of the prop(including also parts 84 and 85) may be spun rapidly into engagement orproximity with the roof.

The upper, internally threaded element 86 is provided at its bottom endwith a continuous annular radially extending flange l9 having adownwardly facing surface I911. The flange l9 forms a dust deflectingledge, note Fig. 2', having a greater diameter than the outside diameterof the adjacent portion of the internally threaded wing nut member 86and extending radially a substantial width overhanging the externalthreads 24 to act as a dust deflector to prevent clogging or jamming ofthe threaded parts under dirty service conditions. Furthermore, by thisconstruction, in which the inner threaded member is open at the bottom,any dust which may collect within the threads is enabled to workdownwardly and to drop out of the threads when the parts are rotatedrelative to one another. This construction also permits the internalthreads 26 of the element 86 toact as wipers to clean off any dust orgrime collecting on the external threads 24. The threads are, to asubstantial extent, self-cleaning, and will operate for long periodsunder extremely dirty conditions without accumulating enough foreignmatter to jam the threads.

Referring now to the hydraulic means, generally designated 8|, attentionis directed first toFig. 2. A base l6 carries upstanding inner and outercylinders 34 and 68, respectively. At its bottom end, the inner cylinderis threadedly engaged with the base, as indicated at 37, and at itsupper end is threadedly engaged with a cover 38, the latter having aflange 39 overlapping and abutting the upper edge of cylinder $8. Theupper end portion of the cover member 38 is formed to receive packing 4iand threaded packing nut 42 for maintaining a liquid-tight seal aboutthe ram screw 83. On the inner end of the latter is a follower or piston82 carrying a resilient, rubberlike or leather, cup member 44 held inplace by washer 46 and nut 47. A hand pump 81 having operating handle49, and piston and cylinder 5| and 52 respectively, is provided forapplying pressure beneath the ram follower to lift the ram screw 83 andapply the final holding load to the ground and roof through shoes 53 and85, respectively. For tilting adjustment of the prop, with respect tothe vertical, the ground shoe 53 may be attached to the base I6 by pivotpin 54 as shown.

Any suitable arrangement of passages and valving inthe base may beemployed for applying hydraulic pressure from the pump to the ramfollower and releasing it when desired. In the present case passage 56(in cylinder member 52) leads through passage 57 to the interior ofcylinder 34 and branches through passage 58 to the annular cross-sectionreservoir 59. Bypass passage 6| connects 5! and 58 and flow therethroughis controlled by valve 62, diagrammatically illustrated. Handle 53controls the opening and closing of valve 82. On the up-stroke of thepump piston 5| fluid is drawn from the reservoir 59 past check valve 64.On the downstroke it is forced past check valve 66 into cylinder 34 anddisplaces the ram follower and the parts carried thereby in an upwarddirection, any fluid on the top side of the ram follower being displacedto the reservoir through low pressure bypass 67. As an overloadprotection, to prevent damage at the upper end of the stroke, acapillary bypass is provided to short circuit high pressure fluid intothe reservoir. When the upper shoe 85 is pressed into contact with theroof it will be so held by check valve 66, which prevents the back flowfrom cylinder 34. When it is desired to release the prop the releasehandle 53 is moved to open valve 52 permitting the fluid beneath thepiston to be displaced into the reservoir as the ram screw movesdownwardly under the weight of itself and of members 86, 84 and 85.

Thus, in operation, when a miner desires to set one of the improvedprops at a particular location, he simply moves valve 62 to closedposition, spins the wing nut member 80, and moves the pump handle 49 upand down until, by its resistance, he knows that a sufficient load isapplied against the ground and roof. To release the prop for removal ata subsequent time, he simply opens valve 62.

From the above it will be apparent that the improved prop constitutes asignificant advance in a field where a single prop has often requiredthe slow and laborious efforts of three or four men operating with longlevers, often in restricted quarters, to emplace and remove it. A singleoperator can emplace and remove the improved prop in less time and do itmore effectively than three men could do with a conventional prop.Furthermore, due to the self-cleaning arrangement of the threaded parts,it will operate for long periods without clogging or jamming, even invery dirty installations.

While but a single embodiment of the present invention has been shownand described it will be apparent to those skilled in the art that manyspecific structural variations may be employed 4 within the spirit ofthe invention. Accordingly the invention should not be understood aslimited to the specific embodiment described, excepting in so far aslimited by the appended claim.

I claim as my invention:

A doubly expandable mine prop comprising a manually extensible screwmeans for quick initial adjustment of the prop and an extensiblehydraulic means for applying a subsequent and final holding loadthereto, said hydraulic means comprising a base, vertically disposedinner and outer cylinders carried by said base in concentric relationdefining a reservoir and a pressure chamber, a piston in said chamber,means for actuating said piston comprising, a pump, conduits and valvemeans connecting said reservoir and chamber in operative relation witheach other, said manually extensible screw means comprising a rodsecured to said piston and having an externally threaded portionextending beyond said chamber, and an internally threaded elementinterengaged with said externally threaded portion of said rod, saidinternally threaded portion having handle means thereon for applyingsaid quick initial adjustment of the prop and a continuous annularradially extending flange adjacent the lower end of said internallythreaded element, said flange providing a ledge having a greaterdiameter than the outside diameter of the adjacent portion of saidinternally threaded element and extending radially a substantial widthand overhanging the external threads of said rod extension to act as adust deflector therefor.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 637,945 Reed Nov. 28, '1899 1,877,364 Schoenburg Sept. 13,1932 1,922,401 Scott Aug. 15, 1933 2,151,057 Suth Mar. 21, 19392,461,810 Curtis Feb. 15, 1949 2,465,653 Leterman Mar. 29, 19492,503,659 Curtis Apr. 11, 1950 2,520,686 Light et al Aug. 29, 19502,584,015 Hawes Jan. 29, 1952

